Greenhouses seen as potential solar dryers

Researchers see a use for Mexico's abandoned greenhouses

Tuesday, January 2, 2018

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Researchers at the National Autonomous University of México (UNAM) have come up with an innovative proposal for the huge number of abandoned greenhouses across the country: modify them for use as solar dryers for fruit, vegetables, flowers and medicinal plants.

An estimated 75% of greenhouses in Mexico are abandoned, meaning that there is plenty of scope to trial the idea.

As to why so many greenhouses are available, the horticultural website Hortalizas suggested that unsuitability for the climate, a lack of information, training and experience about how to use them and commercial mismanagementas reasons why greenhouses in Mexico fail and are consequently abandoned.

But instead of leaving them derelict, scientists from the UNAM Renewable Energy Institute (IER) say that they can be equipped with a solar energy system they have developed, which has the capacity to regulate temperatures inside the greenhouses.

“The system works by capturing and storing solar energy,” Isaac Pilatowsky explained, adding that temperature is regulated according to the amount of air that is allowed to circulate in the greenhouse.

Apart from drying produce, the modified greenhouses could also be used to grow crops in controlled climatic conditions, Pilatowsky explained.

“You need to study case by case because the variables of air quality, humidity and solar radiation all have an influence depending on the time of year,” Pilatowsky said. “What product it is and when it is harvested also matters.”

Now that the technology is available, the UNAM scientist said that the next step is to take it the fields of Mexico, with the end goal being the commercialization of dried products.

However, Pilatowsky was critical of the fact that Mexico lacks laws to regulate such products even though a large quantity of them, such as chiles, are consumed.

“We don’t know what quality they have, because we don’t have regulations that say what the components are and what quality the product must maintain after it has been dehydrated. That’s why they’re not exported,” he said.

The aim of the process was not simply to dry a product, Pilatowsky explained, but to “preserve most of its properties [by] conserving its components and nutrients.”

The researcher also explained that more than 45% of food was wasted in Mexico mainly for reasons related to the manipulation of prices but also because there is a lack of capacity to manipulate, store and transport fresh foods.

“It’s regrettable that we’re throwing out that quantity of product . . . [considering] the nutritional problems there are in the country,” Pilatowsky said.

But along with his IER colleagues, he hopes to change that by recovering fruit and vegetables that are in an advanced stage of ripening and making them fit for consumption through the process of dehydration.

In addition to dried fruits and vegetables and products such as jams, dehydrated products including chiles and medicinal plants can also be turned into nutritional powders, Pilatowsky explained.

“We need to raise awareness of what solar drying can contribute to the agro-industrial sector. We want to take solar energy to another level . . . one that is more productive, with quality control, where these products can be exported,” he remarked.